Colin Farrell, Sam Rockwell, Christopher Walken (right), Woody Harrelson and Tom Waits have joined the cast of "Seven Psychopaths," which McDonagh wrote and is directing, CBS Films announced Wednesday.

Olga Kurylenko ("Ceturion," "Quantum of Solace") is also in negotiations to join the project.

"Seven Psychopaths" is an action-comedy about a struggling screenwriter, to be played by Farrell, who "inadvertently becomes entangled in the Los Angeles criminal underworld after his oddball friends kidnap a gangster's beloved Shih Tzu," according to CBS Films.

Rockwell and Walken play the friends. Harrelson is the gangster.

McDonagh won an Oscar in 2006 for his short film "Six Shooter"; he was also Academy Award-nominated in 2009 for writing "In Bruges."

Blueprint Pictures is producing "Seven Psychopaths." Film4 is co-financing with the BFI Fund and CBS Films, which has U.S. rights to the movie.

Graham Broadbent and Peter Czernin, who produced "In Bruges," are producing.